Effect of Nitrogen-Doped Concentration on the TCR of ITO Thin Films at High Temperature

Ultra-high temperature thin film sensors (UTTSs) are ideally suited on the surface of the hot sections for in-situ measurement at high temperature. Indium tin oxide (ITO), an N-type semiconductor ceramic with a wide band gap, used as the active elements of sensors exhibited a promising application in UTTSs. As one of the most important parameters of UTTSs, temperature coefficient of resistance (TCR) still has many problems to be clarified. In this paper, ITO films were deposited on alumina substrates with Various N
₂
/Ar ambients using magnetron sputtering to investigate the effect of nitrogen-doped concentration on the TCR of ITO films in the temperature range of 50~1200°C.The composition and properties of films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS) and multi-function digital four-probe tester, respectively. The mechanism of TCR curve fluctuation from 50~1200°C with different nitrogen partial pressure was revealed. It was found that more nitrogen-doped concentration can make the TCR more stable at higher temperature.